SX1441EVK Semtech, SX1441EVK Datasheet - Page 20

• Manufacturer Part Number: SX1441EVK
• Description: KIT DEV FOR SX1441
• Manufacturer: Semtech
• Series: EasyBlue™r
• Type: Bluetoothr

Specifications of SX1441EVK

• For Use With/related Products: SX1441
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Contents: -
• Other names: SX1441DVK; SX1441DVK

Personal Area Network
3.5.3 RC Oscillator
The RC oscillator is always turned on and selected for CPU and system operation after a power-on reset or a
negative pulse on pad NRESET. It can be deselected after the SYS_CLOCK_IN or the SLW_CLOCK_IN has been
started and selected as system clock.
The EnableRC bit in the register RegSysClock controls the signal from the RC oscillator. The user can disable the
RC oscillator clock signal by resetting the bit EnableRC.
The RC oscillator frequency is trimmed with the registers RegSysRcTrim1 and RegSysRcTrim2. The absolute
value of the frequency for a given register content may change from chip to chip due to process tolerances.
However, the modification of the frequency as a function of a modification of the register content is fairly precise.
The RC oscillator output frequency, f
The
Note : Values marked with asterisks are not production tested and guaranteed by design.
Table 21 summarizes the characteristics of the oscillator.
Note : Values marked with asterisks are not production tested and guaranteed by design.
Important note: the system is not guaranteed to operate properly with a frequency f
the RC oscillator over this limit may produce unpredictable results.
3.5.4 SLOW_CLOCK_IN
SLW_CLOCK_IN must be present and conform to the Bluetooth specifications if the Bluetooth sequencer deep-
sleep mode is used. It is typically generated by the XE1413 radio chip. Its frequency is 32’000 Hz or 32’768 Hz.
3.5.5 SYS_CLOCK_IN
It is used by the Bluetooth sequencer and the Codec. Its frequency must be 13 MHz with a tolerance of ± 20 ppm.
SYS_CLOCK_IN is typically generated by the XE1413 radio chip.
3.5.6 Clock Source Selection
Different clock sources can be selected independently for the application processor and the reset of the system.
The clock of the Bluetooth sequencer is hard-coded and can not be chosen by the user.
The RC clock is always selected after power-up or a negative pulse on the NRESET pin. The CPU clock selection
is done with the register RegSysClock according to the Table 22. Switching from one clock source to another is
glitch free. See also Figure 11, Figure 12, and Figure 13.
© Semtech 2006
1:0
f
FineStep
CoarseStep
0
(*)
Symbol
RCFine
(*)
(*)
f
RC
=
fo
Internal oscillator frequency
Fine tuning step
Coarse tuning step
⋅
2
RCDivFacto
1
rw
RC
r
Description
Equation 2 - RC oscillator clock frequency
, is obtained by the following trimming rule:
⋅
(
Table 21 – RC oscillator specifications
1
+
Table 20 - RegSysTrim2 register
0000
(
RCCoarse
20
RC fine adjustment
−
) 8
⋅
CoarseStep
Min
5.5
-
-
+
RCFine
8.25
Typ
0.5
7
SX1441 – Bluetooth® 1.2 SoC
RC
greater than 14 MHz. Setting
⋅
FineStep
Max
11
www.semtech.com
)
MHz
%
%
Data Sheet
Unit